1. Field of the Invention
The present invention relates to a switching system such as an Analog Display Service Interface (ADSI), and particularly to a method of recording the bi-directional communication between a customer premises equipment (CPE) and a server of a stored program controlled system (SPCS) in an analog display services interface (ADSI) for facilitating the troubleshooting therein.
2. Description of the Prior Art
Since Alexander Graham Bell performed experiments on a device for sending signals over a conductive wire, the telephone has been growing as a practical device in the modern day. FIG. 1 shows the block diagram of a telephone set. Whenever a caller lifts the handset 10, or referred to as off hook, the telephone network or telephone system is then requested and ready for use by an indicated dial tone. Thereafter, the number of a called party is sent to the telephone network by rotating a dial 12 or by pressing number keys 14. A ringing signal detecting circuit or a ringer 16 in the telephone set of the called party detects the ringing signal and consequently generates some audible tone. After the handset on the called side is lifted, both parties can communicate to each other through transforming sound wave to or from electrical signals by the receiver (earpiece) 18 and the transmitter (mouthpiece) 19.
As the number of the telephones increases, a central office exchange (CO) is established to switch among the telephones. Each telephone is connected to the central office through a local loop consisting of the two wires or four wires. The status of the handset is detected by the CO through this local loop where a dc voltage, usually about 48 volts, is provided by the CO. When the number of the connected telephones further increases, a public switched telephone network is employed to accommodate more telephone connections in an effective manner.
As the telephone network grows larger and more complicated, varieties of functions and services become available. Caller identification (ID) display is a new service available in some modern telephone network, where the caller ID is sent during the beginning of the ringing. Among the many services available today, analog display service interface (ADSI) is one of the interfaces and associated communication protocols for bi-directional transmission of data between a switching system and an customer premises equipment (CPE), which resides and is operated at a custom site for performing intelligent function. Due to a nonperfect public switching network, which switches data between the CPE and a sever on the analog display service side, a nonperfect CPE or the server, error sometimes occurs. Unfortunately, there is no method or equipment for the user to identify the error. A need therefore has been arisen to provide a method to find out where the error comes from and what type the error is, so that an immediate correction can be made.